Shigella cause millions of cases of dysentery (i.e., severe bloody diarrhea) every year, which result in 660,000 deaths worldwide. Shigella dysenteriae serotype 1, one of about 40 serotypes of Shigella, causes a more severe disease with a much higher mortality rate than other serotypes. There are no FDA-licensed vaccines available for protection against Shigella, although a number of institutions are trying various vaccine approaches. The fact that many isolates exhibit multiple antibiotic resistance complicates the management of dysentery infections. The development of an immunogenic composition against Shigella dysenteriae serotype 1 therefore represents a particularly urgent objective.